habitual
by statuscrow
Summary: Killua is a very good listener.


He says goodbye to Alluka around midnight, knowing that Canary will be true to her word and will get rid of all the security footage of his visit by the time he 's left. She and Amane give him small bows on his way out. Killua wonders if the next time he comes to see Alluka he should bring them a souvenir of his adventures with Gon. Even though the trip had been on a whim he'd found the time to pick up a wooden doll for his sister. He wasn't sure what they'd like (Alluka was the only girl he really knew all after all) but Gon might know what to get them.

If Killua had a normal family he might think that it being late meant that no one would be awake, but in a house full of assassins the time didn't really matter. As soon as Canary and Amane were out of sight he had _In_ on, concealing his presence.

There were about a dozen hidden passageways in the Zoldyck Manor, the closest one was through a trapdoor by his old room. Using _In_ the entire time, he's able to make it past several butlers without raising any suspicion. He was just lifting away the rug over the entrance when he remembered Gon asking him about his skateboard the night before. He hadn't thought about it in a while but he'd left one of his old skateboards in his room when he'd run away from home. If he gave it to Gon then maybe they'd get to race when he got back. Silently, he made his way down the hallway towards his old bedroom.

Killua's was pretty sure he'd locked his room before he'd attacked Milluki and his Mom but when he got to it the door was cracked open. Killua froze with his hand a few inches away from the door, a rush of familiar aura pricking across his skin. It wasn't an accident that his room had been left open, someone was in there. Frightened, but a little curious, Killua peaked through the gap.

His eyes had already adjusted to the dark well enough that, with the moonlight coming through the bars on the windows, he can recognize his older brother's back.

Killua took a step back, heart pounding. Had Illumi noticed him?

He watches quietly, unblinking, waiting for him to move but Illumi was sitting on his old bed, leaning back on a hand and clearly not paying attention to his surroundings. He wasn't facing the door but he was moving slightly so his hair was swinging free from his back. Killua swallowed. He was fine, whatever the hell Illumi was doing he wasn't expecting Killua to be home. If he just kept walking no one would know he'd been there.

A quiet sound left Illumi like a sigh and against his will Killua felt his hearing sharpen to make out the noise. His ears catch the heaviness of Illumi's breath and the faint sound of skin against skin and suddenly he knows exactly what he's walked in on.

He's never seen Illumi date anyone so even if Killua _knows_ his brother is technically just as human as he is he's never considered the possibility of him masturbating. He can't imagine what Illumi would think about - doesn't want to imagine the kind of things that turn his brother on. It doesn't matter to him, he should just leave.

"Killu."

Killua's blood runs cold. He was close enough to the trapdoor that maybe he could run for it before Illumi closed in on in on him. The secret passage was dark and cramped enough that Illumi wouldn't make it through if he followed him.

But Illumi doesn't get up or even try to move beyond spreading his legs a little. A cold sweat breaks over his skin when he realizes that Illumi isn't actually aware of his presence at all.

"Aaaa, Killu..." Illumi says again. His voice is so soft that it's only because Killua's hearing is so acute that he catches anything at all.

Killua doesn't want to be here. He doesn't want to watch his brother jerk himself off in his room, on his bed, while thinking about him. He wants to be back in the hotel room that he and Gon were sharing but his body isn't moving. He's not scared of Illumi killing him but there's something frightening about seeing his brother in such a intimate moment. He knows he needs to leave but the weight of Illumi's aura is thick in the air and Killua can't help it, his body reacts the way it always does to his aura and stops moving.

While he's agonizing about trying to leave he hears Illumi's soft moan. His head falls onto his shoulder as he touches himself, his fingers pulling at Killua's sheets.

Killua tries to stop listening, stop focusing his senses on the sound of Illumi gripping his cock but he's trained to pay the most attention when he's scared. Without being able to see for himself he can tell that Illumi uses a lighter grip on his cock than he does on his own just by the sounds his skin makes. That he slicks his hand with something more slippery than spit, and that his pace is even and unrelenting, no matter how turned on he is. He's not trying to imagine it but he's never seen anyone else jerk off before and now he can't stop comparing them. There wasn't lube or lotion in Killua's room before he left so that means Illumi must have brought it with, planning to touch himself on Killua's bed. Is this the first time he's done something like this? Does he normally go to Killua's room for this?

Since he's paying attention he can hear the moment Illumi tightens his hand on his cock. His heart's pounding in his chest and he can smell the faint traces of sweat on Illumi's skin and the slick of his precome.

With some effort he manages to look away but he feels a sudden burst of fear at not having his eyes on Illumi. _Never take your eyes off a threat,_ a voice in his head says. Killua bites his bottom lip and looks up in time to watch Illumi's back go stiff and his hair fall over his shoulders as he bends his head, a small shiver run through his body.

He says Killua's name again when he comes. And Killua watches silently, transfixed.

He has to go. He shouldn't have been there in first place and he definitely wasn't supposed to see what he just saw. Illumi is getting to his feet and moving off to the side, probably to clean himself up so he'll see Killua any second now.

Illumi comes back to his line of sight, not reacting to the sight of his little brother. The door swings open and moonlight fills the hallway.

"Oh, Killu. I didn't know you came by," Illumi says, light and conversational. His clothes are in perfect order and if Killua didn't know better he'd have no idea what he was just doing. "You're getting good at concealing your presence."

Killua doesn't move.

"Are you staying the night?"

Illumi stares at him patiently and, realizing that he expects a response, Killua shakes his head.

"Ah, that's too bad." Killua finches when Illumi approaches. There's no way he doesn't know that Killua saw him touching himself. He stares as Illumi hand, the hand that he'd been jerking himself off with only a minute early, moves towards his face.

Illumi pats his head.

"Well good night then."

Illumi's hand slides down to his face and then away as he walks past him. When he reaches the folded over rug his bends down to fix it. Killua tries to force his body to relax but it won't. He makes himself take several slow even breathes.

"Oh, and Killu?" Illumi calls and slowly Killua turns to face him, this time meeting his eyes. He's smiling lightly. "Come by more often. It's lonely when you aren't around." And then he's gone down the hallways, the heavy black weight of his aura lifting from the air, and Killua -

Killua runs.


End file.
